Water Jet Peening Apparatus and Water Jet Peening Method

ABSTRACT

A water jet peening apparatus (WJP apparatus) includes a seating member, rotating portion set to it, and first and second injection nozzles. A hoisting apparatus is attached to the rotating portion, and the first and second injection nozzles are attached to a nozzle arm. The WJP apparatus is gone down in a reactor vessel (RV) by crane operation, and the seating member is seated on a bottom mounted instrumentation nozzle welded to a bottom head of the RV. By the hoisting apparatus, the nozzle arm is gone down and the first and second injection nozzles are gone down. The first injection nozzle is inserted into the bottom mounted instrumentation nozzle and the second injection nozzle is set outside the bottom mounted instrumentation nozzle. High-pressure water is jetted from the first and second injection nozzles, and WJP is implemented for both of the inner and outer surfaces of the welding area of the bottom mounted instrumentation nozzle.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent application serial no. 2013-146244, filed on Jul. 12, 2013, the content of which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a water jet peening apparatus and a water jet peening method, and more particularly to a water jet peening apparatus and a water jet peening method which are suitably applicable to a tubular member of a nuclear power plant.

2. Background Art

When residual stress exists in a neighborhood of a surface of a welding area or heat-affected zone of a structural member of a nuclear power plant, water jet peening (hereinafter referred to as WJP) is implemented for the welding area and heat-affected zone to improve the tensile residual stress existing in the neighborhood of the surface of the structural member (WJP target) to compressive residual stress. In a state that the structural member the stress of which is to be improved is immersed in water, the WJP is implemented by jetting a high-pressure water jet from an injection nozzle in the water. Shock waves are generated due to collapse of cavitation bubbles included in the water jet jetted from the injection nozzle. The shock waves collide with the surface of the structural member in the water, thus the tensile residual stress in the neighborhood of the surface of the structural member is improved to compressive residual stress. As a result, the initiation of stress corrosion cracking (SCC) in the structural member is suppressed. The stress improvement method by WJP is described, for example, in Japanese Patent Laid-open No. 7 (1995)-270590.

In the stress improvement method described in Japanese Patent Laid-open No. 7 (1995)-270590, the water jet peening apparatus (hereinafter referred to as the WJP apparatus) is seated on an upper end (positioned in the reactor pressure vessel) of a control rod drive mechanism housing, which passes through a bottom of a reactor pressure vessel and is attached to the bottom, and the high-pressure water jet is injected from the injection nozzle of the WJP apparatus toward the welding area between the control rod drive mechanism housing (tubular member) and the reactor pressure vessel. The shock waves generated due to the collapse of the cavitation bubbles included in the high-pressure water jet collide with the surface of the welding area, thus the residual stress on the surface of the welding area is improved. In Japanese Patent Laid-open No. 7 (1995)-270590, it is also described that using the WJP apparatus seated on the upper end of the control rod drive mechanism housing, WJP is implemented for the in core monitor housing (tubular member) adjacent to the control rod drive mechanism housing.

Japanese Patent Laid-open No. 2000-308927 also describes that WJP is implemented for the in core monitor housing. In Japanese Patent Laid-open No. 2000-308927, WJP is implemented for one in core monitor housing adjacent to these control rod drive mechanism housings due to the jets jetted from the respective injection nozzles of the two WJP apparatuses seated in the two control rod drive mechanism housings.

In a WJP method described in Japanese Patent Laid-open No. 7 (1995)-328858, the injection nozzle is inserted into a tubular member, and a jet including cavitation bubbles is jetted toward the inner surface of the welding area of the tubular member from the injection nozzle, and WJP is implemented on the inner surface of the welding area by using the shock waves generated due to the collapse of the cavitation bubbles. As a result, the residual stress of the inner surface of the welding area is improved to compressive residual stress. Also in Japanese Patent Laid-open No. 10 (1998)-76467, the injection nozzle is inserted into a hollow pipe (tubular member) and WJP is implemented on the inner surface of the hollow pipe due to the collapse of the cavitation bubbles included in the jet jetted from the injection nozzle.

CITATION LIST Patent Literature

-   (Patent Literature 1) Japanese Patent Laid-open No. 7 (1995)-270590 -   (Patent Literature 2) Japanese Patent Laid-open No. 2000-308927 -   (Patent Literature 3) Japanese Patent Laid-open No. 7 (1995)-328858 -   (Patent Literature 4) Japanese Patent Laid-open No. 10 (1998)-76467

SUMMARY OF THE INVENTION Technical Problem

The respective WJP apparatuses described in Japanese Patent Laid-open No. 7 (1995)-270590 and Japanese Patent Laid-open No. 2000-308927 can implemented WJP for an outer surface of the tubular member. Further, the respective WJP apparatuses described in Japanese Patent Laid-open No. 7 (1995)-328858 and Japanese Patent Laid-open No. 10 (1998)-76467 can implemented WJP for the inner surface of the tubular member.

However, when implementing WJP on both of the inner and outer surfaces of the tubular member, using the WJP apparatus for outer diameter described in Japanese Patent Laid-open No. 7 (1995)-270590 and Japanese Patent Laid-open No. 2000-308927, WJP is implemented on the outer surface of the tubular member and then using the WJP apparatus for inner diameter described in Japanese Patent Laid-open No. 7 (1995)-328858 and Japanese Patent Laid-open No. 10 (1998)-76467, WJP is implemented on the inner surface of the tubular member. Alternatively, inversely, it can be thought that using the WJP apparatus of the latter, WJP for the inner surface of the tubular member is implemented and then using the WJP apparatus of the former, WJP for the inner surface of the tubular member is implemented.

However, in the implementation of WJP for the inner and outer surfaces of the tubular member, as mentioned above, the WJP apparatus needs to be replaced and the WJP operation requires a long period of time. Therefore, when executing WJP on the inner and outer surfaces of the tubular member, it is desired to shorten the time required for the WJP operation.

An object of the present invention is to provide a water jet peening apparatus and a water jet peening method which can further shorten the time required for water jet peening.

Solution to Problem

A feature of the present invention for attaining the above object is a water jet peening apparatus comprising a seating member; rotating portion rotatably attached to the seating member and set above the seating member; a hoisting apparatus installed on the rotating portion and having a first hoisting member going up and down; a first injection nozzle which is gone up and down by the first hoisting member and is inserted into a tubular member when the seating member is seated on the tubular member which is a water jet peening target; and a second injection nozzle which is attached to the first hoisting member and is set toward outside the tubular member when the seating member is seated on the tubular member.

The first injection nozzle and second injection nozzle are attached to the hoisting member, so that when the seating member is seated on the tubular member which is a water jet peening target, the hoisting is moved by the hoisting apparatus installed on the rotating portion in an axial direction of the tubular member, thus the first injection nozzle can be easily inserted into the tubular member, and the second injection nozzle can be easily set outside the tubular member. High-pressure water is supplied to the first injection nozzle and second injection nozzle, thus, the water jet peening can be implemented on the inner and outer surfaces of the welding area of the tubular member in a state that the seating member is seated on the tubular member. Therefore, the time required for the water jet peening for the inner and outer surfaces of the welding area of the tubular member can be shortened.

Preferably, the water jet peening for the inner and outer surfaces of the welding area of the tubular member is implemented in parallel, thus the time required for the water jet peening can be further shortened.

Advantageous Effect of the Invention

According to the present invention, the time required for the water jet peening for the inner and outer surfaces of the tubular member can be further shortened.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram showing a water jet peening apparatus according to embodiment 1 which is a preferable embodiment of the present invention.

FIG. 2 is an explanatory drawing showing WJP implementation state for a bottom mounted instrumentation nozzle in a reactor vessel using a water jet peening apparatus shown in FIG. 1.

FIG. 3 is an explanatory drawing showing a state where a water jet peening apparatus shown in FIG. 1 is set to a platform.

FIG. 4 is a front view showing a pole holding device viewing from an arrow direction of IV-IV line shown in FIG. 3.

FIG. 5 is a detailed explanatory drawing showing a water jet peening implementation state for welding area between an inner surface of a bottom head of a reactor vessel and a bottom mounted instrumentation nozzle.

FIG. 6 is an enlarged structural diagram showing a swing drive mechanism shown in FIG. 1.

FIG. 7 is an enlarged longitudinal sectional view showing welding area between a bottom head of a reactor vessel and a bottom mounted instrumentation nozzle for which water jet peening shown in FIG. 4 is implemented.

FIG. 8 is a structural diagram showing a water jet peening apparatus according to embodiment 2 which is another preferable embodiment of the present invention.

FIG. 9 is an enlarged view showing IX portion shown in FIG. 8.

FIG. 10 is a structural diagram showing a water jet peening apparatus according to embodiment 3 which is still another preferable embodiment of the present invention.

FIG. 11 is an enlarged side view showing a pole and a cylindrical member included in X portion shown in FIG. 5 and viewing from an arrow direction of Y-Y line shown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention will be explained below.

Embodiment 1

The water jet peening apparatus (hereinafter referred to as WJP apparatus) according to embodiment 1 which is a preferable embodiment of the present invention will be explained by referring to FIGS. 1, 3, and 4. The WJP apparatus of the present embodiment shows an example of the WJP apparatus used in a reactor vessel of a pressurized water nuclear power plant.

A WJP apparatus 1 of the present embodiment is provided with a seating member 2, rotating portion 3, a hoisting apparatus (first hoisting apparatus) 12, injection nozzles 19 and 20, a swing drive mechanism 21, high-pressure pumps 27A and 27B, and high-pressure hoses 28A and 28B.

The rotating portion 3 is attached rotatably to an upper end of the seating member 2 using a bearing. The rotating portion 3 includes a frame 4, a casing 6, a cylindrical member 10, and a rotating drive apparatus (for example, motor) 11. The casing 6 is structured in such a way that a bottom member 7 is attached to a lower end of a cylindrical member (for example, a cylindrical member having a square cross section) 44 and that a top member 9 is attached to an upper end of the cylindrical member 44. A space 8 is formed in the cylindrical member 44. The cylindrical member 10 with a closed upper end portion is installed on a top of the top member 9 of the casing 6. The rotating drive apparatus 11 is set in space 8 in the casing 6 and is attached to a lower surface of the top member 9. A rotary shaft of the rotating drive apparatus 11 is extended into the cylindrical member 10 and a pinion (not shown) attached to the rotary shaft of the rotating drive apparatus 11 engages with the gear formed overall the periphery of an inner surface of the cylindrical member 10.

The frame 4 includes an equipment frame 5 extending in the axial direction of the WJP apparatus 1 and a platy rotation support member 30. The rotation support member 30 is attached at a lower end of the equipment frame 5 and is attached rotatably to the upper end of the seating member 2 using a bearing. The equipment frame 5 is attached to a lower surface of the bottom member 7.

The hoisting apparatus 12 includes a trapezoidal screw 14 that is a rod, a nozzle arm (first hoisting member) 16, and a hoisting drive apparatus (for example, a motor) 13. A lower end portion of the trapezoidal screw 14 is attached rotatably to a support member 15 attached to the equipment frame 5 and an upper end of the trapezoidal screw (first trapezoidal screw) 14 is attached rotatably to a support member 59 attached to the equipment frame 5. The hoisting drive apparatus (first hoisting drive apparatus) 13 is set in the space 8 of the casing 6 and is attached to the top of the bottom member 7. A rotary shaft of the hoisting drive apparatus 13 is connected to the trapezoidal screw 14 via a reducer (not shown). A nut (not shown) installed on a nozzle arm 16 engages with the trapezoidal screw 14. The nozzle arm 16 is movably attached to the trapezoidal screw 14 via the nut.

The injection nozzle 19 for an inner surface of a tubular member (a water jet peening target (hereinafter referred to as a WJP target)) and the injection nozzle 20 for an outer surface of the tubular member are attached to the nozzle arm 16. The injection nozzle 19 is attached to a connection member 25 attached to the nozzle arm 16 and is extended downward from the connection member 25. A lower end portion of the injection nozzle 19 is inserted into a through hole formed in the support member 15. An upper end portion of the injection nozzle 19 is connected to the high-pressure hose 28B via the connection member 25. A support member 18 with an upper end portion thereof attached to the nozzle arm 16 is extended downward from the nozzle arm 16. In the present embodiment, the rotating portion 3 and the hoisting apparatus 12 are shared by the injection nozzle 19 and the injection nozzle 20.

The swing drive mechanism 21 is attached to the lower end portion of the casing 18. As shown in detail in FIG. 6, the swing drive mechanism (swivel unit) 21 includes a casing 60, a motor 22, a water chamber 23, and a rotary shaft 24. The casing 60 is installed at the lower end of the support member 18 and the water chamber 23 is attached to a side surface of the casing 60. The rotary shaft 24 is rotatably attached to the casing 60 and the water chamber 23. The rotary shaft of the motor 22 is coupled to an end portion of the rotary shaft 24 on the side of the casing 60 via a reducer 66 and the rotation of the motor 22 is transferred to the rotary shaft 24. The injection nozzle 20 is attached to the rotary shaft 24. A water supply region (not shown) is formed in the water chamber 23 and the water supply region is connected to the high-pressure hose 28A connected to the water chamber 23. The interval between the water chamber 23 and the rotary shaft 24 is sealed to prevent a water leak. A high-pressure water supply path 67 formed in the rotary shaft 24 is connected to the water supply region in the water chamber 23 and the injection nozzle 20.

A Cable Bear (registered trademark) 17 is set on an upper end portion of a support member 26 attached to the upper end of the nozzle arm 16. The high-pressure hoses 28A and 28B are held by the Cable Bear 17 and are connected separately to high-pressure pumps 27A and 27B.

The WJP method for each of the inner and outer surfaces of a plurality of bottom mounted instrumentation nozzles (tubular member) 32 which pass through a bottom head of a reactor vessel 31 of the pressurized water nuclear power plant and are attached to the bottom head using the WJP apparatus 1 will be explained by referring to FIGS. 2 to 7.

After the operation of the pressurized water nuclear power plant is stopped due to outage or another reason, a closure head (not shown) of a reactor vessel 31 is removed and multiple fuel assemblies and reactor internals which are located in the reactor vessel 31 are removed from the reactor vessel 31 and are kept in a predetermined storage area. A platform 52 is set across the reactor vessel 31 in the prestressed concrete containment vessel (not shown) surrounding the reactor vessel 31 and is installed movably on an refueling floor formed in the upper portion in the prestressed concrete containment vessel (refer to FIG. 2). In the reactor vessel 31, cooling water 39 is filled.

In the WJP apparatus 1, the closed lower end portion of the cylindrical member 10 is attached rotatably to the top member 9 by a bearing (not shown). The WJP apparatus 1 is held by a plurality of poles 29 connected to the upper end of the cylindrical member 10. The plurality of poles 29 are extended downward by being successively connected, thus the WJP apparatus 1 descends toward the bottom head of the reactor vessel 31 in the reactor vessel 31. The length of one pole 29 is set at 2 m so as to be easily handled. The upper end of the pole 29 in the uppermost position is hanged down by a crane 57 installed in the prestressed concrete containment vessel (refer to FIG. 2).

The mutual connection operation of the plurality of poles 29 will be explained below. Firstly, the pole 29 connected to the upper end of the cylindrical member 10 (the pole 29 that will be placed in the lowermost position when the WJP apparatus 1 is seated on the bottom mounted instrumentation nozzle 32 which is the WJP target) is hanged down by the crane 57 and the WJP apparatus 1 is immersed in the cooling water 39. A flange 71 positioned at a lower end of this pole 29 is attached to a flange 72 positioned at an upper end of the cylindrical member 10. A supporting apparatus (not shown) with a holding apparatus (not shown) attached thereto is attached to the platform 52. The upper end of the pole 29 hanged down by the crane 57 is held by the holding apparatus and the held pole 29 is removed from the crane 57. Another pole 29 is connected to the upper end of the pole 29 held by the holding apparatus, and the upper end of the connected pole 29 is hanged on the hook of the crane 57. In this state, the pole 29 held by the holding apparatus is separated from the holding apparatus. The crane 57 is operated and the pole 29 hanged on the crane 57 is lowered. By repeating such an operation, the plurality of poles 29 are connected successively and the WJP apparatus 1 is lowered in the reactor vessel 31. A marking line 47 is drawn on the side surface of the flange 72 of the cylindrical member 10 just above the injection nozzle 20 (refer to FIG. 11). A marking line 47, which is one straight line extending in the axial direction of the pole 29, is also drawn on side surface of flange 71 of the pole 29 and outer surface of pole 29 (refer to FIG. 11). In this connection operation, the WJP apparatus 1 and poles 29 are connected so that that the direction of the marking lines be oriented in the same direction. Thus direction (relative position) of the injection nozzle 20 and the marking line 47 drawn on the outer surface of the uppermost pole 29 fit in. The direction of the injection nozzle 20 installed in the connected WJP apparatus 1 and poles 29 can be adjusted remotely by rotating the pole 29 as described hereafter.

The WJP apparatus 1 is positioned right above the bottom mounted instrumentation nozzle 32 for implementing WJP by operating the crane 57 and then is seated at the upper end of the bottom mounted instrumentation nozzle 32.

In a state where the WJP apparatus 1 is seated at the upper end of the bottom mounted instrumentation nozzle 32, the pole 29 in the uppermost position among the plurality of connected poles 29 is held by a pole holding apparatus 40 attached to an upper handrail member 55 and a lower handrail member 56 of the platform 52 (refer to FIG. 3). The platform 52 includes a floor member 53 and a fence installed on the floor member 53. The fence has a constitution that it includes a plurality of bar members 54 attached to the top of the floor member 53 perpendicularly to the periphery of the floor member 53; the upper ends of these bar member 54 are connected by the upper handrail member 55; and the center portion of each bar member 54 in the longitudinal direction is connected by the lower handrail member 56.

Here, the structure of the pole holding apparatus 40 will be explained by referring to FIGS. 3 and 4. The pole holding apparatus 40 includes a table 41, a rotation holder 42, and a handrail attaching portion 48. The table 41, the rotation holder 42, and the handrail attaching portion 48 are mutually attached removably. The table 41 is attached to the top of a base 49 integrated with the handrail attaching portion 48. The rotation holder 42 is set rotatably to the table 41. A rotating angle scale 43 is indicated on a side surface of the rotation holder 42 (refer to FIG. 4). A plurality of (for example, two) fixing screws 46 are attached to the rotation holder 42. A pair of handles 45 is attached on the rotation holder 42. The handrail setting portion 48 includes a frame 50 and an arm 51. An upper end portion of the frame 50 is attached to the base 49 and the arm 51 is attached to a lower end portion of the frame 50.

Processes that the pole holding apparatus 40 is attached to the pole 29 and the platform 52 will be explained below. The rotation holder 42 of the halved structure is loaded on the pole 29 which is hanged on the crane 57 and set in the uppermost position, and then fixed to the pole 29 by fixing the plurality of fixing screws 46. At this time, the rotation holder 42 is positioned above the upper handrail member 55 of the fence of the platform 52. The base 49 is seated on the upper handrail member 55 and the upper handrail member 55 is inserted into a groove formed in the lower surface of the base 49 integrated with the handrail attaching portion 48. The table 41 is set on the base 49. At this time, the table 41 is in contact with the base 49. The fixing screws 46 are loosened, and the rotation holder 42 is lowered along the pole 29, and the rotation holder 42 is seated on the table 41. After the rotation holder 42 is seated on the table 41, the arm 51 of the handrail attaching portion 48 is fixed to the lower handrail member 56.

A marking line 47 which is one straight line extending in the axial direction of the pole 29 is drawn on the outer surface of the pole 29 attached to the rotation holder 42 (refer to FIG. 4). The marking line 47 is fit to 0° of the rotating angle scale 43 of the rotation holder 42, and each of the fixing screws 46 is fixed, and the pole 29 is clamped by the rotation holder 42. In this state, an operator on the floor member 53 of the platform 52 rotates a handle 45 and fits the direction of the injection nozzle 20 to the initial standard position (at the position of the injection nozzle 20 shown by the solid line in FIG. 7, an injection outlet of the injection nozzle 20 is directed toward the center of the reactor vessel 31) in the reactor vessel 31 while looking at the angle of the rotating angle scale 43 where the marking line 47 is positioned. In this way, the injection outlet of the injection nozzle 20 is set in a predetermined direction. As mentioned above, the attaching of the pole holding apparatus 40 to the pole 29 and the platform 52 is finished. Thereafter, WJP to the bottom mounted instrumentation nozzle 32 is implemented.

When the seating member 2 is seated at the upper end of the bottom mounted instrumentation nozzle 32 which is a WJP target, the upper end portion of the bottom mounted instrumentation nozzle 32 welded to the bottom head of the reactor vessel 31 is inserted into an insertion hole 34 formed in the seating member 2 (refer to FIG. 5). The injection nozzle 19 positioned right above the bottom mounted instrumentation nozzle 32 and the injection nozzle 20 are come down.

The hoisting drive apparatus 13 of the hoisting apparatus 12 is driven to turn the trapezoidal screw 14. At this time, the nozzle arm 16 engaging with the trapezoidal screw 14 by the nut descends and the injection nozzle 19 is inserted into the bottom mounted instrumentation nozzle 32 inserted into the insertion hole 34 through a through hole 33 formed in the seating member 2. The injection outlet of the injection nozzle 20 is positioned outside the bottom mounted instrumentation nozzle 32 in the reactor vessel 31 and is toward the outer surface of a welding area 58 between the bottom mounted instrumentation nozzle 32 and the reactor vessel 31 (refer to FIG. 7). The injection nozzle 19 and the injection nozzle 20 are gone up and down simultaneously by the hoisting apparatus 12. The motor 22 of the swing drive mechanism 21 is driven to rotate the rotary shaft 24, and the inclination angle of the injection nozzle 20 is adjusted so that the injection outlet of the injection nozzle 20 faces the outer surface of the welding area 58. As mentioned above, the position of the injection outlet of the injection nozzle 20 in the axial direction of the reactor vessel 31 is adjusted by the hoisting apparatus 12 and the swing drive mechanism 21.

When the target position of a jet 36 (refer to FIG. 5) jetted from the injection outlet of the injection nozzle 20, as shown in FIG. 7, is a position 61A on the outer surface of the welding area, the target position of a jet 35 (refer to FIG. 5) jetted from the injection outlet of the injection nozzle 19 inserted into the bottom mounted instrumentation nozzle 32, as shown in FIG. 7, becomes a position 62A for the inner surface of the bottom mounted instrumentation nozzle 32. Further, when the target position of the jet 36 from the injection nozzle 20 is a position 61B on the outer surface of the welding area as shown in FIG. 7 after the injection nozzle 20 is rotated by 180° from the position 61A, the target position of the jet 35 from the injection nozzle 19, as shown in FIG. 7, becomes a position 62B for the inner surface of the bottom mounted instrumentation nozzle 32. So that the target position of the jet 36 from the injection nozzle 20 and the corresponding target position of the jet 35 from the injection nozzle 19 can be adjusted, the lower end of the injection nozzle 19 is positioned below the lower end of the injection nozzle 20 and the fine adjustment of both positions is executed by the rotation of the injection nozzle 20 in the vertical direction by the swing drive mechanism 21.

After the respective positions of the injection nozzles 19 and 20 in the axial direction of the reactor vessel 31 are set to predetermined positions, the high-pressure pumps 27A and 27B are driven. The injection nozzle 20, for example, is set at the position shown by the solid line in FIG. 7. High-pressure water pressurized by the high-pressure pump 27A is supplied to the injection nozzle 20 through the high-pressure hose 28A. The high-pressure water becomes the jet 36 from the injection nozzle 20 and is jetted toward the outer surface of the welding area 58 in the cooling water 39 in the reactor vessel 31. Many cavitation bubbles are included in the jet 36, and when the cavitation bubbles are collapsed, shock waves are generated. The shock waves collide with the outer surface of the welding area 58, and WJP is implemented on the outer surface of the welding area 58, and compressive residual stress is given to the outer surface thereof. In this way, the residual stress of the outer surface of the welding area 58 is improved.

When the high-pressure water is supplied from the high-pressure pump 27A to the injection nozzle 20, the high-pressure water pressurized by the high-pressure pump 27B is supplied to the injection nozzle 19 in the bottom mounted instrumentation nozzle 32 through the high-pressure hose 28B. The high-pressure water becomes the jet 35 from the injection nozzle 19 and is jetted toward the inner surface of the welding area 58 in the cooling water 39 in the bottom mounted instrumentation nozzle 32. The jet 35 also includes many cavitation bubbles and shock waves generated due to the collapse of the cavitation bubbles collide with the inner surface of the welding area 58, and WJP is implemented on the inner surface of the welding area 58, and compressive residual stress is formed on the inner surface thereof. In this way, the residual stress of the inner surface of the welding area 58 is improved. In the present embodiment, WJP can be implemented simultaneously on the inner and outer surfaces of the welding area 58 of the reactor vessel 31 and the bottom mounted instrumentation nozzle 32. Further, the lower end of each of the bottom mounted instrumentation nozzle 32 is closed and leakage of the cooling water 39 in the reactor vessel 31 to the outside through each of the bottom mounted instrumentation nozzle 32 is prevented.

While the injection nozzles 19 and 20 jet the jets 35 and 36 respectively, the rotating drive apparatus 11 is driven. The rotary force of the rotating drive apparatus 11 is transferred to the cylindrical member 10 to rotate the cylindrical member 10 around the center axis of the cylindrical member 10. By the rotation of the cylindrical member 10, the frame 4 and the casing 6 above the seating member 2, that is, the rotating portion 3 rotate. As a result, the nozzle arm 16 rotates, so that the injection nozzle 20 rotates, for example, by 180° clockwise around the bottom mounted instrumentation nozzle 32. The injection nozzle 19 also rotates in the same direction in the bottom mounted instrumentation nozzle 32. By the rotation of such nozzles 19 and 20 for jetting each jet, WJP is implemented within the respective ranges of 180° of the inner and outer surfaces of the welding area 58. When the injection nozzle 20 moves from the solid line position shown in FIG. 7 to the dotted line position due to such a rotation of the injection nozzle 20, the nozzle arm 16 is gone down by the hoisting apparatus 12 in accordance with the curved surface of the bottom head of the reactor vessel 31 from the solid line position to the dotted line position.

In the method mentioned above, for the zone of 180° of the inner and outer surfaces of the welding area 58, WJP is implemented, and then the rotating drive apparatus 11 is reversely rotated, and the injection nozzle 20 is rotated counterclockwise along the outside surface of the bottom mounted instrumentation nozzle 32. After the injection nozzle 20 is returned to the solid line position shown in FIG. 7, the injection nozzle 19 for jetting the jet 35 and the injection nozzle 20 for jetting the jet 36 are rotated counterclockwise, with jetting the jets 35 and 36 respectively, by the driving force of the rotating drive apparatus 11 until the injection nozzle 20 reaches the dotted line position in FIG. 7.

Therefore, the injection nozzle 20 and others are rotated, thus WJP can be implemented on overall the periphery of the inner and outer surfaces of the welding area 58 and the residual stress of the inner and outer surfaces of the welding area 58 can be improved.

Upward reaction force generated by jetting jets from the injection nozzles 19 and 20 can be supported by the own weight of the WJP apparatus 1 and the fixing of the poles 29 to the upper handrail member 55 and the lower handrail member 56 of the platform 52 using the pole holding apparatus 40.

After the implementation of WJP on the inner and outer surfaces of the welding area 58 for one bottom mounted instrumentation nozzle 32 is completed, the driving of the high-pressure pumps 27A and 27B is made to stop, and the hoisting apparatus 12 is driven, and the injection nozzles 19 and 20 are raised, and the injection nozzle 19 is moved to a position above the upper end of the bottom mounted instrumentation nozzle 32. Each fixing screw 46 is loosened, and the poles 29 are gone up by the crane 57, and the seating member 2 is moved to a position above the upper end of the bottom mounted instrumentation nozzle 32. When the seating member 2 reaches the position above the upper end of the bottom mounted instrumentation nozzle 32, the operation of the crane 57 is made to stop, and the platform 52 is moved horizontally. Furthermore, the operator on the platform 52 moves the base 49 horizontally along the upper handrail member 55, so that the injection nozzle 19 is positioned right above bottom mounted instrumentation nozzle 32 in the order of predetermined locations. As mentioned above, the WJP apparatus 1 is gone down by the crane 57, and the seating member 2 is seated at the upper end of the aforementioned bottom mounted instrumentation nozzle 32. The hoisting apparatus 12 is driven to lower the nozzle arm 16, and the injection nozzle 19 is inserted into the bottom mounted instrumentation nozzle 32 through the through hole 33. Thereafter, as mentioned above, each injection nozzle jets a jet and WJP is implemented on the inner and outer surfaces of the welding area 58 of the bottom mounted instrumentation nozzle 32.

In this way, WJP is implemented sequentially on the inner and outer surfaces of the welding area 58 of each of the bottom mounted instrumentation nozzle 32 installed on the bottom head of the reactor vessel 31.

The WJP apparatus 1 of the present embodiment includes the injection nozzle 19 for inner surface and the injection nozzle 20 for outer surface and these injection nozzles are installed on the rotating portion 3, so that it can implement WJP on both of the inner and outer surfaces of the bottom mounted instrumentation nozzle 32 which is a tubular member. That is, the injection nozzle 19 is disposed inside the bottom mounted instrumentation nozzle 32, and the injection nozzle 20 is disposed outside the bottom mounted instrumentation nozzle 32, thus WJP can be implemented simultaneously on the inner surface and outer surface of the bottom mounted instrumentation nozzle 32. WJP in the present embodiment, compared with the conventional method where WJP for the inner and outer surfaces of the bottom mounted instrumentation nozzle 32 is implemented using one WJP apparatus having the injection nozzle for the inner surface and another WJP apparatus having the injection nozzle for the outer surface, there is no need to exchange the WJP apparatus and WJP for the inner surface and the outer surface of the bottom mounted instrumentation nozzle 32 can be implemented simultaneously, so that the time required for the implementation of WJP on the inner and outer surfaces of the bottom mounted instrumentation nozzle 32 can be shortened remarkably compared with the conventional WJP method.

In the present embodiment, the injection nozzles 19 and 20 are attached to the hoisting member (the nozzle arm 16) of the hoisting apparatus 12 installed in the rotating portion 3 and the rotating portion and hoisting apparatus of the injection nozzles 19 and 20 are shared. As a result, they the injection nozzles 19 and 20 can be gone up and down simultaneously while the injection nozzles 19 and 20 are rotated. Therefore, even when the welding area 58 is different in height in the position of the bottom mounted instrumentation nozzle 32 attached to the curved portion of the bottom head of the reactor vessel 31 on the side of the center of the reactor vessel 31 and the position outside the reactor vessel 31, on the 180° opposite side to former position, the hoisting member with the injection nozzles 19 and 20 attached is gone up and down, thus each injection nozzle can be gone up and down along the curved surface of the bottom head of the reactor vessel 31 while these injection nozzles are rotated. Therefore, WJP along the curved surface of the bottom head of the reactor vessel 31 can be implemented appropriately on such inner and outer surfaces of the welding area 58.

Since the through hole 33 interconnected with the bottom mounted instrumentation nozzle 32 is formed in the seating member 2, when the WJP apparatus 1 is gone down and the seating member 2 of the WJP apparatus 1 is seated at the upper end of the bottom mounted instrumentation nozzle 32, the injection nozzle 19 can be inserted easily into the bottom mounted instrumentation nozzle 32 via the through hole 33 formed in the seating member 2.

The pole 29 to be attached to the WJP apparatus 1 is attached to the platform 52 by the pole holding apparatus 40, so that when the injection nozzles 19 and 20 jet the jets at the time of implementation of WJP, the WJP apparatus 1 can be prevented from moving in the rotation direction of the nozzle 20 and in the horizontal direction. The load of the WJP apparatus 1 is held by the crane 57.

The straight marking line 47 is given onto the outer surface of the pole 29 and the rotating angle scale 43 is given onto the rotation holder 42 to be attached to the platform 52, so that the direction of the injection outlet of the injection nozzle 20 can be adjusted and controlled easily by fitting the marking line 47 to a predetermined angle of the rotating angle scale 43.

The injection nozzles 19 and 20 are rotated by the common rotating portion 3 and are installed on the common hoisting apparatus 12, so that there is no need to install separately a control panel for the injection nozzles 19 and 20, and the rotation operation of the rotating portion and the hoisting operation of the hoisting apparatus 12 can be controlled by one control panel. Thus, the WJP apparatus 1 can be made compact.

Embodiment 2

The water jet peening apparatus according to embodiment 2 which is another preferable embodiment of the present invention will be explained by referring to FIGS. 8 and 9. A WJP apparatus 1A of the present embodiment is an example of the WJP apparatus used in the reactor vessel of the pressurized water nuclear power plant.

The WJP apparatus 1A of the present embodiment has a structure that a long guide 64 of the nozzle arm 16 protruded downward with the nut engaging with the trapezoidal screw 14 and a hoisting member (second hoisting member) 63 moving in the vertical direction along the guide 64 are added to the WJP apparatus 1 of embodiment 1. A connection member 25 is attached to the hoisting member 63. The other structure of the WJP apparatus 1A is the same as that of the WJP apparatus 1 of embodiment 1.

WJP for the inner and outer surfaces of the welding area 58 of the bottom mounted instrumentation nozzle 32 attached to the bottom head having a curved surface of the reactor vessel 31 using the WJP apparatus 1A is implemented similarly to embodiment 1. In the present embodiment, the injection nozzles 19 and 20 move vertically together by going up and down vertically the nozzle arm (the first hoisting member) 16 by the hoisting apparatus (first hoisting apparatus) 12, and the injection nozzle 19 can be gone up and down independently by the hoisting member 63.

Since the bottom head of the reactor vessel 31 forms a curved surface, in the welding area 58 of the bottom mounted instrumentation nozzle 32 with the bottom head of the reactor vessel 31, a height difference H (refer to FIGS. 5 and 7) of the position of the bottom mounted instrumentation nozzle 32 on the side of the center of the bottom head of the reactor vessel 31 and the position outside the reactor vessel 31, on the 180° opposite side to former position, is different in the neighborhood of the center of the bottom head of the reactor vessel 31 and in an outer position of the reactor vessel 31. The height difference H in the neighborhood of the center of the reactor vessel 31 is smaller than that in the outer position of the reactor vessel 31. That is, the height difference H increases with distance from the center of the bottom head of the reactor vessel 31. When the height difference H is small, it can be implemented without interferences of injection nozzle 20 and the bottom head of reactor vessel 31 by the rotation of the injection nozzle 20 in the axial direction of the bottom mounted instrumentation nozzle 32 by the swing drive mechanism 21. However, when the height difference H is large, it cannot be implemented only by the operation of the swing drive mechanism 21 because of interferences of injection nozzle 20 and the bottom head of reactor vessel 31.

In the present embodiment, the difference in the height difference H due to the installation position of the bottom mounted instrumentation nozzle 32 in the bottom head of the reactor vessel 31 can be resolved by going up and down the injection nozzle 19 by the hoisting member 63. The hoisting member 63 is moved vertically by a hoisting apparatus (second hoisting apparatus) 70 installed on the nozzle arm 16. The hoisting apparatus 70, similarly to the hoisting apparatus 12, includes a hoisting drive apparatus (for example, motor) 72 being a second hoisting drive apparatus and a trapezoidal screw (second trapezoidal screw) 73 that is a rod interconnected to the hoisting drive apparatus 72. The hoisting drive apparatus 72 is attached to a top surface of the nozzle arm 16. The trapezoidal screw 73 is set in parallel with trapezoidal screw 14 and is attached rotatably to the nozzle arm 16. An upper end portion of the trapezoidal screw 73 is coupled to the hoisting drive apparatus 72 and a lower end portion of the trapezoidal screw 73 is supported rotatably by the nozzle arm 16. A nut 74 attached to hoisting member 63 is engaged with the trapezoidal screw 73.

When implementing WJP for the welding area 58 of the bottom mounted instrumentation nozzle 32 located in the outer position of the reactor vessel 31 which is larger in the height difference H than the bottom mounted instrumentation nozzle 32 located in the neighborhood of the center of the bottom head of the reactor vessel 31, the hoisting drive apparatus 72 installed on the nozzle arm 16 is driven to turn the trapezoidal screw 73, and by the turning of the trapezoidal screw 73, the hoisting member 63 including the nut 74 engaging with the trapezoidal screw 73 is gone down along the guide 64 in an axial direction of the trapezoidal screw 73. The injection nozzle 19 is gone in concert with the hoisting member 63. By doing this, the distance along the reactor vessel 31 axial direction between the lower end position of the injection nozzle 19 and the lower end of the injection nozzle 20 is increased. The descent of the injection nozzle 19 by the hoisting member 63 is executed before or after the injection nozzle 19 is inserted into the bottom mounted instrumentation nozzle 32. For example, after the distance between the lower end of the injection nozzle 19 and the lower end of the injection nozzle 20 is spread by the hoisting member 63, downward the nozzle arm 16 by the hoisting apparatus 12, thus the injection nozzles 19 and 20 can be descended. The injection nozzle 19 is inserted into the bottom mounted instrumentation nozzle 32 and the injection nozzle 20 is positioned toward the outside surface of the welding area 58 outside the bottom mounted instrumentation nozzle 32.

While high-pressure water is supplied to the injection nozzles 19 and 20 to jet the jets 35 and 36 respectively, each nozzle is rotated, and similarly to embodiment 1, WJP is executed overall the peripheries of the respective inner surface and outer surface of the welding area 58 of the bottom mounted instrumentation nozzle 32.

Thereafter, when implementing WJP for the welding area 58 of the bottom mounted instrumentation nozzle 32 positioned in the neighborhood of the center of the bottom head of the reactor vessel 31 having a small height difference H, the hoisting member 63 is gone up by driving the hoisting drive apparatus 72 and the distance between the lower end of the injection nozzle 19 and the lower end of the injection nozzle 20 is reduced. By doing this, better WJP can be implemented on the inner and outer surfaces of the welding area 58 of the bottom mounted instrumentation nozzle 32 positioned in the neighborhood of the center of the bottom head of the reactor vessel 31 having a small height difference H.

The present embodiment can obtain each effect generated in embodiment 1. In the present embodiment, among the injection nozzles 19 and 20 held by the nozzle arm 16 which is a common hoisting member, the injection nozzle 19 can be independently gone up and down by the hoisting member 63 and hoisting apparatus 70, so that WJP for the inner and outer surfaces of the welding area 58 can be implemented satisfactorily for the welding area 58 different in the height difference H.

Embodiment 3

The water jet peening apparatus according to embodiment 3 which is still another preferable embodiment of the present invention will be explained by referring to FIG. 10. A WJP apparatus 1B of the present embodiment is an example of the WJP apparatus used in the reactor vessel of the pressurized water nuclear power plant.

The WJP apparatus 1B of the present embodiment has a structure that in the WJP apparatus 1 of embodiment 1, switching valves 65A and 65B are respectively installed on the high-pressure hoses 28A and 28B connected with one common high-pressure pump 27A. The other structure of the WJP apparatus 1B is the same as the structure of the WJP apparatus 1.

Even in the present embodiment, similarly to embodiment 1, the injection nozzle 19 is inserted into the bottom mounted instrumentation nozzle 32, and the injection nozzle 20 is set outside the bottom mounted instrumentation nozzle 32, and WJP for the inner surface and the outer surface of the welding area 58 is implemented. In the present embodiment, the way of supplying high-pressure water to the injection nozzles 19 and 20 is different from embodiment 1 and WJP for the inner and outer surfaces of the welding area 58 cannot be implemented simultaneously. For example, the switching valve 65B is closed, and the switching valve 65A is opened. High-pressure water pressurized by the high-pressure pump 27 is supplied to the injection nozzle 20. By doing this, the jet 36 is jetted from the injection nozzle 20 and WJP for the outside surface of the welding area 58 is implemented. After WJP is implemented on overall the outer side of the welding area 58, the switching valve 65B is opened, and the switching valve 65A is closed. By doing this, the high-pressure water discharged from the high-pressure pump 27A is supplied to the injection nozzle 19 which is inserted into and rotated in the bottom mounted instrumentation nozzle 32, and is jetted into the bottom mounted instrumentation nozzle 32 as the jet 35. As a consequence, WJP for the inner surface of the bottom mounted instrumentation nozzle 32 is implemented.

The present embodiment can obtain the effects generated in embodiment 1. However, in the present embodiment, WJP cannot be implemented simultaneously on the inner and outer surfaces of the welding area 58, like embodiment 1, so that the time required for the implementation of the WJP becomes longer than embodiment 1. However, there is no need to exchange the WJP apparatus for the inner surface of the bottom mounted instrumentation nozzle 32 for the WJP apparatus for the outer surface of the bottom mounted instrumentation nozzle 32, so that the time required for the implementation of WJP can be shortened from that of the conventional WJP.

REFERENCE SIGNS LIST

-   1, 1A, 1B: water jet peening apparatus, 2: seating member, 3:     rotating portion, 4: frame, 6: casing, 11: rotating drive apparatus,     12, 70: hoisting apparatus, 13, 72: hoisting drive apparatus, 14,     73: trapezoidal screw, 16: nozzle arm, 19, 20: injection nozzle, 21:     a swing drive mechanism, 27A, 27B: high-pressure pump, 28A, 28B:     high-pressure hose, 29: pole, 30: rotation support member, 31:     reactor vessel, 32: bottom mounted instrumentation nozzle, 40: pole     holding apparatus, 41: table, 42: rotation holder, 43: rotating     angle scale, 46: fixing screw, 47: marking line, 49: base, 50:     frame, 52: platform, 63: hoisting member, 65A, 65B: switching valve. 

What is claimed is:
 1. A water jet peening apparatus comprising: a seating member; rotating portion rotatably attached to said seating member and set above said seating member; a first hoisting apparatus installed on said rotating portion and having a first hoisting member going up and down; a first injection nozzle which is gone up and down by said first hoisting member and is inserted into a tubular member which is a water jet peening target when said seating member is seated on said tubular member; and a second injection nozzle which is attached to said first hoisting member and is set outside said tubular member when said seating member is seated on said tubular member.
 2. The water jet peening apparatus according to claim 1, wherein a through hole into which said first injection nozzle is inserted is formed on said seating member.
 3. The water jet peening apparatus according to claim 1, wherein a second hoisting apparatus having a second hoisting member going up and down is attached to said first hoisting member; and wherein said first injection nozzle is attached to said second hoisting member.
 4. The water jet peening apparatus according to claim 1, wherein said second injection nozzle is attached to said first hoisting member via a swing drive mechanism for swing in said second injection nozzle in an axial direction of the water jet peening apparatus.
 5. The water jet peening apparatus according to claim 1, comprising: a high-pressure pump; a first high-pressure hose connected to said first injection nozzle; a second high-pressure hose connected to said second injection nozzle; and a switching valve device for switching and connecting said first hose and said second hose to an outlet of said high-pressure pump.
 6. The water jet peening apparatus according to claim 1, comprising: a high-pressure pump; a first high-pressure hose connected to said first injection nozzle; a second high-pressure hose connected to said second injection nozzle; a first on-off valve installed on said first hose; and a second on-off valve installed on said second hose.
 7. A water jet peening method for implementing water jet peening on inner and outer surfaces of a welding area among a tubular member installed on a bottom of a reactor vessel and said reactor vessel by using a water jet peening apparatus having a seating member; rotating portion rotatably attached to said seating member and set above said seating member; a first hoisting apparatus installed on said rotating portion and having a first hoisting member going up and down; a first injection nozzle which is gone up and down by said first hoisting member and is inserted into said tubular member; and a second injection nozzle which is attached to said first hoisting member and is set outside said tubular member, comprising steps of: seating said seating member on said tubular member in said reactor vessel filled with water; going down said first hoisting member; inserting said first injection nozzle into said tubular member, and setting said second injection nozzle outside said tubular member; jetting a water jet from said first injection nozzle and implementing water jet peening on said inner surface of said welding area, and jetting a water jet from said second injection nozzle and implementing water jet peening for said outer surface of said welding area.
 8. The water jet peening method according to claim 7, comprising steps of: using said water jet peening apparatus wherein a second hoisting apparatus having a second hoisting member going up and down is attached to said first hoisting member; and said first injection nozzle is attached to said second hoisting member; adjusting a distance between said first injection nozzle and said second injection nozzle in an axial direction of said reactor vessel by moving said second hoisting member in said axial direction by said second hoisting apparatus; and jetting said jets from said first injection nozzle and said second injection nozzle with said adjusted distance to implement said water jet peening.
 9. The water jet peening method according to claim 7, comprising step of: jetting said jet from said second injection nozzle when said jet is jetted from said first injection nozzle.
 10. The water jet peening method according to claim 7, comprising steps of: holding a pole attached to an upper end portion of said water jet peening apparatus by using a rotation holding member of a pole holding apparatus attached to a hand rail of a platform set above said reactor vessel; and rotating said rotation holding member and adjusting a direction of a injection outlet of said second injection nozzle. 